U.S. patent number 10,329,962 [Application Number 15/877,437] was granted by the patent office on 2019-06-25 for internal combustion engine system.
This patent grant is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. The grantee listed for this patent is TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Noriyasu Adachi, Takayoshi Kawai, Kaoru Otsuka, Shinji Sadakane, Keisuke Sasaki, Hiroyuki Sugihara, Shigehiro Sugihira.
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United States Patent |
10,329,962 |
Kawai , et al. |
June 25, 2019 |
Internal combustion engine system
Abstract
At crank angle CA10 at which the switch request of the drive cam
was issued, the ejection operations of the pins at all the solenoid
actuators started simultaneously. The ejected pins are seated on
the cam carriers at crank angle CA12. The pin seated on the cam
carrier moves along the grooves in accordance with the rotation of
the cam carrier. The earliest finish timing of the switch operation
of the drive cam is at crank angle CA13 (#4 cylinder). At the crank
angle CA13, drive of the fuel injector and the ignition device in
each cylinder is permitted.
Inventors: |
Kawai; Takayoshi (Susono,
JP), Adachi; Noriyasu (Numazu, JP),
Sugihira; Shigehiro (Susono, JP), Sasaki; Keisuke
(Susono, JP), Otsuka; Kaoru (Mishima, JP),
Sadakane; Shinji (Susono, JP), Sugihara; Hiroyuki
(Suntou-gun, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
TOYOTA JIDOSHA KABUSHIKI KAISHA |
Toyota-shi, Aichi-ken |
N/A |
JP |
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Assignee: |
TOYOTA JIDOSHA KABUSHIKI KAISHA
(Toyota-shi, Aichi-ken, JP)
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Family
ID: |
63449906 |
Appl.
No.: |
15/877,437 |
Filed: |
January 23, 2018 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20180274393 A1 |
Sep 27, 2018 |
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Foreign Application Priority Data
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Mar 23, 2017 [JP] |
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2017-057792 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01L
1/08 (20130101); F01L 13/0015 (20130101); F02D
41/0002 (20130101); F01L 13/0036 (20130101); F01L
1/047 (20130101); F02D 41/00 (20130101); Y02T
10/40 (20130101); F02D 41/062 (20130101); F02D
2041/001 (20130101); F01L 2013/0052 (20130101); F02D
2041/0092 (20130101); F16H 53/025 (20130101); F01L
2800/01 (20130101); F01L 2820/042 (20130101); F01L
2820/041 (20130101); F01L 2820/04 (20130101) |
Current International
Class: |
F01L
1/34 (20060101); F01L 1/08 (20060101); F01L
13/00 (20060101); F02D 41/00 (20060101); F01L
1/047 (20060101); F16H 53/02 (20060101); F02D
41/06 (20060101) |
Field of
Search: |
;123/90.16,90.18,90.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2009-228543 |
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Oct 2009 |
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JP |
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2010-168966 |
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Aug 2010 |
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JP |
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2013-148012 |
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Aug 2013 |
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JP |
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Primary Examiner: Chang; Ching
Attorney, Agent or Firm: Sughrue Mion, PLLC
Claims
What is claimed is:
1. An internal combustion engine system comprising: an internal
combustion engine comprising multiple cylinder; multiple types of
cams which have different cam profiles per cylinder and are
configured to drive intake valves which are provided in each
cylinder; cam carriers which are provided on a cam shaft which
rotates synchronously with a crank shaft of the internal combustion
engine, each of the cam carriers supports the multiple types of
cams per cylinder or cylinder groups, wherein a spiral-shaped
groove is formed on an outer periphery of each of the cam carriers,
the spiral-shaped groove comprises an inclined part which inclines
with respect to the cam shaft, a front orthogonal part which is
orthogonal to the cam shaft and communicates with the inclined part
on a front side in the rotation direction of the cam shaft and a
rear orthogonal part which is orthogonal to the cam shaft and
communicates with the inclined part on a rear side in the rotation
direction of the cam shaft; multiple switching mechanisms which are
provided corresponding to the cam carriers and are configured to:
slide the cam carriers sequentially in the axial direction of the
cam shaft in accordance with ejection operations of pins which are
configured to engage with the spiral-shaped groove; and switch
drive cams that actually drive the intake valves among the multiple
types of the cams; and a control device, wherein the control device
is configured to: when operating the switching mechanisms during
non-engine start, execute a cylinder discrimination based on
information about rotation positions of the crank shaft and the cam
shaft and determine start timing of ejection operations of the pins
based on the result of the cylinder discrimination; and when
operating the switching mechanisms during engine start, start to
perform the ejection operations of the pins so that at least one of
the pins is ejected from at least one of the switching mechanisms
before the execution of the cylinder discrimination.
2. The internal combustion engine system according to claim 1,
wherein the control device is also configured to, when operating
the switching mechanisms during the engine start, permit combustion
in all cylinders or cylinder groups when a retraction operation of
at least one of the pins which is ejected from at least one of the
switching mechanisms is completed.
3. The internal combustion engine system according to claim 1,
wherein the internal combustion engine system further comprising a
motor which is configured to rotate the crank shaft during the
engine start, wherein the control device is also configured to:
when operating the switching mechanisms during the engine start,
start the ejection operations of the pins in all the switching
mechanisms before the execution of the cylinder discrimination; and
drive the motor after the ejected pins from all of the switching
mechanisms are seated on the cam carriers.
4. The internal combustion engine system according to claim 3,
wherein the control device is also configured to start the ejection
operations of the pins in all the switching mechanisms at the same
timing.
5. The internal combustion engine system according to claim 1,
wherein the control device is also configured to: sequentially
start the ejection operations of the pins for each mechanism group
obtained by dividing the switching mechanisms into at least two
mechanism groups; and permit combustion in all cylinders or
cylinder groups when the retraction operation of at least one of
the pins is completed which was ejected from a switching mechanism
belonging to a mechanism group whose order of the ejection
operation is the last of the mechanism groups.
6. The internal combustion engine system according to claim 5,
wherein the control device is also configured to start the ejection
operations of the pins belonging to a second mechanism group after
the ejection operations of the pins belonging to a first mechanism
group are completed.
Description
CROSS-REFERENCE TO RELATED APPLICATION
The present disclosure claims priority under 35 U.S.C. .sctn. 119
to Japanese Patent Application. No. 2017-57792, filed on Mar. 23,
2017. The contents of this application are incorporated herein by
reference in their entirety.
BACKGROUND
Technical Field
The present disclosure relates to an internal combustion engine
system.
Background Art
JP 2009-228543 A discloses a variable valve device for a
multi-cylinder engine in which two types of intake cams having
different lift amounts (specifically, large lift cams and small
lift cams) are used for driving an intake valve of each cylinder.
In the valve device, the two types of intake cams are carried by
cam carriers. The cam carriers are slidably provided in an axial
direction of a cam shaft. When the cam carriers slide in the axial
direction of the cam shaft, the intake cams are switched
therebetween to change the lift amount of the intake valve. The cam
carriers are also provided for each cylinder group and slide in
order of the cylinder group. In other word, in the valve device, a
switch of the intake cams is performed in order of units of the cam
carriers.
JP 2010-168966 A discloses an engine start control with a valve
device in which one type of intake cam is continuously changeable
in a lift amount and an operation angle. This start control is
performed for increasing the lift amount of the intake valve to a
predetermined value or more when the engine is restarted after
automatic stop of the engine. JP 2010-168966 A also discloses an
example of the start control for driving the valve device in which
the lift amount of the intake cam is maximum immediately before the
automatic stop of the engine.
JP 2013-148012 A discloses a cylinder discrimination method at an
engine start of a four-stroke typed engine. In the cylinder
discrimination method, compression top dead center TDC of each
cylinder is specified based on signals from a crank angle sensor
and a cam angle sensor while a starter is driven to rotate a crank
shaft and a cam shaft during the engine start. The crank shaft and
the cam shaft are provided with a rotor (specifically, a crank
rotor and a cam rotor). Since the rotor includes chipped tooth
parts and positions of the chipped tooth parts are known
beforehand. Therefore, the compression top dead center of each
cylinder is specified by obtaining the signals on the chipped tooth
parts.
In the multi-cylinder engine provided with the intake cams in which
cam profiles such as a lift amount and an operation angle are
switched, it is desirable that the cam profiles of all the intake
cams of all the cylinders become a suitable cam profile for
starting the engine (hereinafter, also referred to as a "starting
cam profile") when the engine is started. In other words, it is
desirable that the cam profiles of all the intake cams are switched
to the starting cam profile before the engine is started.
The start control of JP 2010-168966 A enables the cam profiles of
all the intake cams to be switched to the starting cam profile
before the engine is started. However, the switching to the
starting cam profile is not necessarily successful. If the
switching fails, the combustion in a cylinder corresponding to the
intake cam which failed in the switching is not appropriately
performed, and the engine start-up performance may be reduced.
A measure to solve such a problem, the switching is performed again
when the engine is restarted. Here, in the system in which intake
cams are sequentially switched on the cam carriers as disclosed in
JP 2009-228543 A, it is important for ensuring switching accuracy
to perform the cylinder discrimination as disclosed in JP
2013-148012 A. However, to perform such cylinder discrimination, it
is necessary to wait until information about the chipped tooth
parts of the crank rotor and the cam rotor is obtained. Therefore,
it takes time to complete the cylinder discrimination and the slide
of the cam carries cannot be started until cylinder discrimination
is done. Therefore, there is a possibility of leading to engine
start delay.
The present disclosure addresses the above problem, and an object
of the present disclosure is to suppress the start delay of the
engine due to the switching to the starting cam profile in the
multi-cylinder engine in which cam profiles are switched in order
of units of the cam carriers.
SUMMARY
The present disclosure provides an internal combustion engine
system comprising an internal combustion engine comprising multiple
cylinder, multiple types of cams, cam carriers, multiple switching
mechanisms, and a control device.
The multiple types of cams have different cam profiles per
cylinder. The multiple types of cams are configured to drive intake
valves which are provided in each cylinder.
The cam carriers are provided on a cam shaft which rotates
synchronously with a crank shaft of the internal combustion engine.
Each of the cam carriers supports the multiple types of cams per
cylinder or cylinder groups.
On an outer periphery of each of the cam carriers, a spiral-shaped
groove is formed. The spiral-shaped groove comprises an inclined
part which inclines with respect to the cam shaft and a front
orthogonal part which is orthogonal to the cam shaft and
communicates with the inclined part on a front side in the rotation
direction of the cam shaft, and a rear orthogonal part which is
orthogonal to the cam shaft and communicates with the inclined part
on a rear side in the rotation direction of the cam shaft.
The switching mechanisms are provided corresponding to the cam
carriers. The switching mechanisms are configured to slide the cam
carriers sequentially in the axial direction of the cam shaft in
accordance with ejection operations of pins which are configured to
engage with the spiral-shaped groove. The switching mechanisms are
also configured to switch drive cams that actually drive the intake
valves among the multiple types of the cams.
The control device is configured to operate the switching
mechanisms. The control device is also configured to, when
operating the switching mechanisms during non-engine start, execute
a cylinder discrimination based on information about rotation
positions of the crank shaft and the cam shaft and determine start
timing of ejection operations of the pins based on the result of
the cylinder discrimination. The control device is also configured
to, when operating the switching mechanisms during engine start,
start to perform the ejection operations of the pins so that at
least one of the pins is ejected from at least one of the switching
mechanisms before the execution of the cylinder discrimination.
When the ejection operations of the pins are started before the
execution of the cylinder discrimination, it is possible to
suppress a delay in completion timing of the switching of the drive
cams as compared with a case where the ejection operation is
started after the execution of the cylinder discrimination is
executed.
The control device may be configured to, when operating the
switching mechanisms during the engine start, permit combustion in
all cylinders or cylinder groups when a retraction operation of at
least one of the pins which is ejected from at least one of the
switching mechanisms is completed.
When combustion in all cylinders or cylinder groups are permitted
when the retraction operation of at least one of the pins which is
ejected from at least one of the switching mechanisms is completed,
it is possible to suppress a delay in first combustion timing of
the internal combustion engine.
The internal combustion engine system may comprise a motor which is
configured to rotate the crank shaft during the engine start.
The control device may be configured to, when operating the
switching mechanisms during the engine start, start the ejection
operations of the pins in all the switching mechanisms before the
execution of the cylinder discrimination and drive the motor after
the ejected pins from all of the switching mechanisms are seated on
the cam carriers. The control device may be configured to start the
ejection operations of the pins in all the switching mechanisms at
the same timing.
When the motor is driven after the ejected pins from all of the
switching mechanisms are seated on the cam carriers, the motor
starts to rotate after the ejected pins are seated on the cam
carriers. Therefore, the ejected pins are able to engage with the
spiral-shaped grooves with high probability. Further, when the
ejection operations of the pins in all the switching mechanisms is
started at the same timing, the ejected pins are able to seat on
the cam carriers at substantially the same timing. Therefore, the
ejected pins are able to engage with the spiral-shaped grooves with
high probability.
The control device may be configured to, when operating the
switching mechanisms during the engine start, sequentially start
the ejection operations of the pins for each mechanism group
obtained by dividing the switching mechanisms into at least two
mechanism groups. The control device may also be configured to
permit combustion in all cylinders or cylinder groups when the
retraction operation of at least one of the pins is completed which
was ejected from a switching mechanism belonging to a mechanism
group whose order of the ejection operation is the last of the
mechanism groups. The control device may also be configured to
start the ejection operations of the pins belonging to a second
mechanism group after the ejection operations of the pins belonging
to a first mechanism group are completed.
Even when there are constraints that the ejection operations of the
pins of all switching mechanisms cannot be executed at the same
timing, the switching of the drive cams can be executed by
sequentially starting the ejection operations of the pins for each
mechanism groups. When the ejection operations of the pins are
sequentially started for each mechanism groups, when combustion in
all cylinders or cylinder groups are permitted when the retraction
operation of at least one of the pins is completed which was
ejected from a switching mechanism belonging to a mechanism group
whose order of the ejection operation is the last of the mechanism
groups, it is possible to suppress the delay in first combustion
timing of the internal combustion engine. Even when there is an
electric restriction, the switching of the drive cams can be
executed by starting the ejection operations of the pins belonging
to the second mechanism group after the ejection operations of the
pins belonging to the first mechanism group are completed.
As mentioned above, according to the internal combustion system of
the present disclosure, it is possible to suppress the start delay
of the engine due to the switching to the starting cam profile.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a schematic diagram for describing a configuration
example of a system according to a first embodiment of the present
disclosure;
FIGS. 2A to 2D each are a diagram for describing an example of a
rotational operation of a cam carrier 12 by an engagement between a
pin 20 and a groove 18 shown in FIG. 1;
FIG. 3 is a diagram for describing an example of a relationship
between a switch operation of a drive cam and four strokes of an
engine;
FIG. 4 is a diagram for describing an example of the switch
operation of the drive cam in a normal state of an engine according
to the first embodiment of the present disclosure;
FIGS. 5 and 6 each are a diagram for describing an example of a
processing routine relevant to a start control executed by an ECU
in the first embodiment of the present disclosure;
FIG. 7 is a diagram for describing an example of the switch
operation of the drive cam during an engine start according to the
first embodiment of the present disclosure;
FIG. 8 is a diagram for describing a problem in a case where it is
assumed that the switch operation in the normal state of the engine
described with reference to FIG. 4 is performed during the engine
start;
FIG. 9 is a diagram for describing another example of the switch
operation of the drive cam during the engine start according to the
first embodiment of the present disclosure;
FIG. 10 is a diagram for describing an example of a processing
routine relevant to the start control executed by the ECU in a
second embodiment of the present disclosure;
FIGS. 11 and 12 each are a diagram for describing an example of a
processing routine relevant to the start control executed by the
ECU in a third embodiment of the present disclosure;
FIG. 13 is a diagram for describing an example of the switch
operation of the drive cam during the engine start according to the
third embodiment of the present disclosure;
FIG. 14 is a diagram for describing a cam carrier including three
types of intake cams and a configuration of a solenoid actuator to
be combined with the cam carrier; and
FIG. 15 is a diagram for describing an example of a switch
operation of the drive cam during the engine start on the premise
of the cam carrier shown in FIG. 14.
DESCRIPTION OF EMBODIMENTS
Hereinafter, embodiments of the present disclosure will be
described based on the drawings. Note that the common elements in
each drawing are assigned the same reference numerals,
respectively, and the duplicate description is omitted.
First Embodiment
Firstly, a first embodiment of the present disclosure will be
described with reference to FIGS. 1 to 9.
[Description of System Configuration Example]
FIG. 1 is a schematic diagram for describing a configuration
example of a system according to the first embodiment of the
present disclosure. The system shown in FIG. 1 is an internal
combustion engine system which is mounted on a vehicle. The
internal combustion engine is a four-stroke type reciprocating
engine and it is also a straight four-cylinder type engine. An
ignition order of the engine is a first cylinder (#1 cylinder), a
third cylinder (#3 cylinder), a fourth cylinder (#4 cylinder), and
a second cylinder (#2 cylinder). The number of cylinders of the
engine may be two, three, or five or more. The ignition order of
the engine is not particularly limited.
A valve system shown in FIG. 1 includes a cam shaft 10. The cam
shaft 10 is connected with a crankshaft (not shown), and is rotated
in synchronism with the crankshaft. Four cam carriers 12 are
arranged at intervals on the cam shaft 10, each of the cam carriers
having a hollow shaft formed therein. The cam carriers 12 are
slidably arranged in an axial direction of the cam shaft 10 while
being fixed in a rotational direction of the cam shaft 10. The cam
carrier 12 includes two types of intake cams 14 and 16 that have
different cam profiles profile means at least one of a lift amount
and an operation angle, the same shall apply hereinafter), the
intake cams 14 and 16 being provided adjacently to each other.
In the first embodiment, the intake cam 14 has an operation angle
and a lift amount that are smaller than those of the intake cam 16,
for example. Hereinafter, the intake cam 14 and the intake cam 16
are also called as a "small cam 14" and a "large cam 16",
respectively, for the convenience of description. Two pairs of
small and large cams 14 and 16 are provided for each cylinder. This
is because two intake valves are disposed for each cylinder. In the
present disclosure, however, the number of intake valves per
cylinder may be one, or three or more.
A surface of the cam carrier 12 has a groove 18 formed thereon and
spirally extending while rotating in the axial direction of the cam
shaft 10. The grooves 18 respectively provided on the cam carriers
are formed with a phase difference among the cylinders.
Specifically, the phase difference of 90.degree. is provided
between the groove 18 for #1 cylinder and the groove 18 for #3
cylinder, between the groove 18 for #3 cylinder and the groove 18
for #4 cylinder, between the groove 18 for #4 cylinder and the
groove 18 for #2, and between the groove 18 #2 cylinder and the
groove 18 for #1 cylinder. The two of the branches of the groove 18
for each cylinder join one in the middle. Hereinafter, when
distinguishing the portions of the groove 18 from each other, a
part after joining is referred to as groove 18a, and a part before
joining is referred to as grooves 18b and 18c. The depth of the
groove 18a is constant in the middle portion. However, the depth of
the groove 18a is not constant from the middle portion to the end
portion. From the middle portion to the end portion, the depth of
the groove 18a is formed so as to become shallower toward the end
portion.
The valve system shown in FIG. 1 includes a solenoid actuator 24
having two pins 20 and 22 and a coil for each cylinder. The pins 20
and 22 are composed of magnetic body. When energizing the coil, the
pin 20 (or the pin 22) is ejected from the solenoid actuator 24.
The ejected pin 20 (or the ejected pin 22) is seated on the groove
18b (or the groove 18c) and the ejected pin 20 (or the ejected pin
22) engages with the groove 18.
When the pin 20 (or the pin 22) in the engaged state is pushed from
the shallow end portion of the groove 18a, the pushed pin 20 (or
the pushed pin 22) is returned to the solenoid actuator 24. Because
of current flow in the coil, an induced electromotive force is
generated when the pin 20 (or the pin 22) is pushed back to the
solenoid actuator 24. When the induced electromotive force is
detected, the energization to the coil is cut off. When the
energization to the coil is cut off, the pin 20 (or the pin 22) is
retracted into the solenoid actuator 24 and the engagement state
between the pin 20 (or the pin 22) and the groove 18 is canceled.
Hereinafter, when there is particularly no need to distinguish
between the pins 20 and 22, the pins 20 and 22 are simply referred
to as "pins".
[Description of Rotational Operation Example of Cam Carrier]
FIGS. 2A to 2D each are a diagram for describing an example of a
rotational operation of the cam carrier 12 by engagement between
the pin 20 and the groove 18. In FIGS. 2A to 2D, assume that the
cam carrier 12 is rotated from an upper side to a lower side. For
the convenience of description, FIGS. 2A to 2D each illustrate only
the cam carrier 12 and the solenoid actuator 24, and rocker arm
rollers 30 that come into contact with the small cam 14 and the
large cam 16. In FIG. 2A, both of the pins 20 and 22 are retracted
into the solenoid actuator 24. The pin 20 is positioned to face the
groove 18b, whereas the pin 22 is positioned to face a part of the
cam carrier 12 here the groove 18 is not formed.
FIG. 2B illustrates a posture of the cam carrier 12 that is rotated
by 90.degree. from a state shown in FIG. 2A. As being understood by
a comparison between FIG. 2B and FIG. 2A, when the cam carrier 12
is rotated, the groove 18a moved to a back side of the cam carrier
12, whereas the grooves 18b and 18c are moved to a front side of
the cam carrier 12. The grooves 18b and 18c shown in FIG. 2B are
orthogonal to the shaft of the cam carrier 12. In FIG. 2B, the pin
20 is ejected from the solenoid actuator 24 and is seated on the
groove 18b. An ejection operations of the pins 20 is started so
that the pin 20 seats on a part where the groove 18b is orthogonal
to the axis of the cam carrier 12 (hereinafter also referred to as
an "orthogonal part"). The pin 20 ejected from the solenoid
actuator 24 is smoothly inserted into the orthogonal part of the
groove 18b and engaged with the groove 18b.
FIG. 2C illustrates a posture of the cam carrier 12 that is rotated
by 90.degree. from a state shown in FIG. 2B. As being understood by
a comparison between FIG. 2C and FIG. 2B, when the cam carrier 12
is rotated, the whole area of the groove 18a is completely moved to
the back side of the cam carrier 12, whereas the grooves 18b and
18c are further moved to the front side of the cam carrier 12. As
being understood by a comparison between FIG. 2C and FIG. 2B, the
cam carrier 12 is slid in a left direction. This is because the pin
20 in the engagement state with the groove 18b moves with the
rotation of the cam carrier 12 along a part where the groove 18b is
inclined with respect to the axis of the cam carrier 12
(hereinafter also referred to as an "inclined part").
FIG. 2D illustrates a posture of the cam carrier 12 that is rotated
by 90.degree. from a state shown in FIG. 2C. As being understood by
a comparison between FIG. 2D and FIG. 2C, when the cam carrier 12
is rotated, the inclined parts of the grooves 18b and 18c are moved
to the back side of the cam carrier 12. In FIG. 2D, the pin 20
engages with the groove 18a. The pin 20 in the engagement state
with the groove 18a moves with the rotation of the cam carrier 12
to the shallow end portion of the groove 18a. When the pin 20 moves
to the shallow end portion of the groove 18a, the pin 20 is pushed
from the shallow end portion and goes back to the solenoid actuator
24 side. When the pin 20 is pushed back, the induced electromotive
force is generated. When signal due to the generation of the
induced electromotive force (hereinafter also referred to as
"return signal") is detected, the energization to the coil is
interrupted and the pin 20 is retracted into the solenoid actuator
24.
As being understood from FIGS. 2A to 2D, when the cam carrier 12 is
slid in the left direction, a cam with which the rocker arm roller
26 comes into contact (hereinafter also referred to as a "drive
cam") is switched from the small cam 14 to the large cam 16.
A switch operation from the large cam 16 to the small 14 is
performed as follows. The cam carrier 12 is further rotated from
the state shown in FIG. 2D, and the pin 22 is ejected from the
solenoid actuator 24. The ejection operation of the pun 22 is
started so that the pin 22 is seated on the orthogonal part of the
groove 18c. The pin 22 which is ejected from the solenoid actuator
24 by the energization to the coil engages with the orthogonal part
of the groove 18c. When the pin 22 in the engagement state with the
groove 18c moves along the groove 18c, the cam carrier 12 is slid
in a right direction. When the pin 22 moves from the groove 18c to
the shallow end portion the groove 18a, the pin 22 is pushed from
the shallow end portion. When the pin 22 is pushed back, the
induced electromotive force is generated. Then, when the return
signal is detected, the energization to the coil is interrupted and
the pin 22 is retracted into the solenoid actuator 24. Finally, the
drive cam is switched from the large cam 16 to the small cam
14.
Referring back to FIG. 1, the system configuration example is
continuously described. The system shown in FIG. 1 includes an ECU
40 as a control device. The ECU 40 includes a RAM (random access
memory), a ROM (read only memory), a CPU (microprocessor), and the
like. The ECU 40 receives and processes signals from various
sensors mounted on a vehicle. The various sensors include a crank
angle sensor 42 that outputs a signal in accordance with a rotation
angle of the crankshaft. The various sensors also include an
acceleration position sensor 44 that outputs a signal in accordance
with a stepping amount of an accelerator pedal. The various sensors
also include an ignition key 46 that outputs a signal for starting
an engine (hereinafter also referred to as an "IG signal").
The ECU 40 processes the signals received from the various sensors,
and operates various actuators in accordance with a predetermined
control program. The various actuators include the solenoid
actuators 24 mentioned above. The various actuators also include
fuel injection valves 30 and ignition devices 32 which are provided
in each cylinder of the engine. The various actuators also include
a starter motor (hereinafter also referred to as a "starter"). The
starter 34 is a well-known starting device which makes the
crankshaft rotate by receiving driving power from a battery (not
shown).
[Description of Switch Operation Example of Drive Cam]
In the first embodiment, the small cams 14 are mainly used to drive
the intake valves during a normal state of the engine. However, the
large cams 16 are surely used to drive the intake valves when the
engine is started. FIG. 3 is a diagram for describing an example of
a relationship between a switch operation of a drive cam and four
strokes of an engine. Note that the switch operation of the drive
cam in #1 cylinder will be described in FIG. 3, the switch
operation of the drive cam in #2 to #4 cylinders is basically the
same as that of #1 cylinder.
The switch operation of the drive cam in #1 cylinder is executed
while the cam shaft (or the cam carrier) is about one revolution.
As an example, the switch operation of the drive cam in #1 cylinder
is started in the middle stage of the exhaust stroke shown on the
left side of FIG. 3. The middle stage of the exhaust stroke
corresponds to crank angle immediately before the pin faces to the
orthogonal part of the groove 18b (or the groove 18c). The ejection
operation of the pin is started at this crank angle.
The ejection operation of the pin is finished in the initial stage
of the intake stroke shown on the right side of FIG. 3. When the
ejection operation is finished, the pin becomes in a full stroke
condition. The pin in the full stroke condition is seated on the
orthogonal part of the groove 18b (or the groove 18c). When the
crank angle at which the ejection operation of the pin is started
is changed, crank angle at which the pin in the full stroke
condition is seated on the orthogonal part of the groove 18b (or
the groove 18c) can be changed arbitrarily within a "pin insertion
section" shown in FIG. 3. Then, the pin which is seated on the
orthogonal part of the groove 18b (or the groove 18c) moves from
here to the inclined part of the groove 18b (or the groove
18c).
When the pin moves along the inclined part of the groove 18b (or
the groove 18c), the switch operation of the drive cam is
substantially executed within a "cam switch section" shown in FIG.
3. The pin which moves along the inclined part of the groove 18b
(or the groove 18c) reaches the groove 18a in the initial stage of
the exhaust stroke shown in the right side of FIG. 3. Then the
retraction operation of the pin is started in the late stage of the
exhaust stroke. The retraction operation of the pin is executed
within a "pin retraction section" shown in FIG. 3 and is finished
in the late stage of the intake stroke shown in the right side of
FIG. 3. Thereby the switch operation of the drive cam in #1
cylinder is also finished.
[Switch Operation Example in Normal State of Engine]
FIG. 4 is a diagram for describing an example of the switch
operation of the drive cam in a normal state of an engine according
to the first embodiment of the present disclosure. The switch
operation of the drive cam is executed in response to a switch
request. The switch operation of the drive cam is actually started
after a cylinder discrimination in response to the switch request.
The cylinder discrimination is executed with signals of the crank
angle sensor and the cam angle sensor.
The cylinder discrimination will be described. As shown in the
upper part of FIG. 4, the signal from the crank angel sensor (crank
angle signal) is pulsed shape corresponding to protrusions on a
crank rotor. In the first embodiment, the protrusions are provided
at intervals of 15.degree. CA. Therefore, the crank angle signal
shown in FIG. 4 occurs every time the crank shaft rotates by
15.degree. CA. However, there is only one chipped tooth part on the
crank rotor. Because of the chipped tooth part, the crank angle
signal is not generated at 120.degree. CA and 480.degree. CA. In
one cycle (=720.degree. CA) of the engine, the crank shaft rotates
twice. Therefore, there are two crank angle sections per cycle in
which no crank angle signal is generated.
Like the crank angle signal, signal of the cam angle sensor (cam
angle signal) is pulsed shape corresponding to protrusions on a cam
rotor. In the first embodiment, there are three protrusions
provided in the cam rotor. Therefore, in FIG. 4, the cam angle
signal due to the protrusions occurs from 60.degree. CA to
240.degree. CA, from 420.degree. CA to 480.degree. CA, and from
600.degree. CA to 720.degree. CA (=0.degree. CA). It should be
noted that the cam shaft makes one revolution while the crank shaft
rotates twice. Therefore, when paying attention only to the cam
rotor, it is understood that its first protrusion is provided in a
range of 30.degree. to 120.degree., its second protrusion is
provided in a range of 210.degree. to 240.degree., its third
protrusion is provided in a range of 300.degree. to
360.degree..
As shown near to the cam angle signal in FIG. 4, the cam angle
signal which correspond to the chipped tooth parts of the crank
angle signal is either "HI" or "LO". In the first embodiment, the
cylinder discrimination is made as to which of the four strokes the
current state of each cylinder is based on the result of the cam
angle signal. The positions of the protrusions of the crank rotor
and the cam rotor are known in advance. Therefore, when the cam
angle signal obtained by the chipped tooth part of the crank angle
signal is "HI" (120.degree. CA), it can be specified that #1
cylinder is in the expansion stroke, #3 cylinder is in the
compression stroke, #4 cylinder is in the intake stroke, and #2
cylinder is in the exhaust stroke. When the cam angle signal
obtained by the chipped tooth part of the crank angle signal is
"LO" (480.degree. CA), it can be specified that #1 cylinder is in
the intake stroke, #3 cylinder is in the exhaust stroke, #4
cylinder is in the expansion stroke, and #2 cylinder is in the
compression stroke.
Assume that the switch request for the drive cam is issued at crank
angle CA0 shown FIG. 4. Then, the cylinder discrimination is
executed based on the cam angle signal "LO" Which is obtained
immediately after the crank angle CA0 due to the chipped tooth part
(crank angle CA1). After the cylinder discrimination, the switch
operation of the drive cam in #3 cylinder is executed at the crank
angle CA2. Also, in accordance with an ignition order of the
engine, the switch operations in the other cylinders are executed
at crank angle CA3 (#4 cylinder), crank angle CA4 (#2 cylinder) and
crank angle CA5 (#1 cylinder). Each of the switch operation of the
drive cam is finished at crank angle CA6 (#3 cylinder), crank angle
CA7 (#4 cylinder), crank angle CA8 (#2 cylinder) and crank angle
CA9 (#1 cylinder).
[Characteristics of Control in First Embodiment]
In the system in which the small cam is mainly driven during the
normal state of the engine, it is assumed that the small cam is
selected as the drive in many cases where a stop request for the
engine (a stop request for driving the fuel injector and the
ignition device, the same shall apply hereinafter) is issued.
Therefore, in the first embodiment, it is determined whether or not
a cylinder to which the small cam is selected as the drive cam
(hereinafter, also referred to as a "small cam cylinder") is
included when the stop request for the engine is issued. And, when
it is determined that the small cam cylinder is included, the
switch request for the drive cam is issued. Hereinafter, such
control during the engine stop is also called "stop control". In
the stop control of the first embodiment, the switch request for
the drive cam is issued for all for all of the solenoid actuators.
Based on the switch request, the switch operation of the drive cam
described in FIG. 4 is executed.
However, since the stop request for the engine is issued, the
rotation of the cam shaft is stopped even during the stop control.
When the rotation of the cam shaft stops during the stop control,
the switch operation of the drive cam based on the switch request
is incomplete in some of the small cam cylinder. According to the
first embodiment in which priority is given to the engine stop
rather than the stop control, fuel consumption can be suppressed as
compared with a case where the priority order is reversed. On the
other hand, when the engine is started with failure of the switch
operation, there is a possibility that combustion state may
deteriorate in the small cam cylinder. Also, due to the unevenness
of the drive cam among the cylinders, there is a possibility that
the combustion state varies among the cylinders.
Therefore, in the first embodiment, when a start request for the
engine is issued, a determination with the same contents as the
determination on the small cam cylinder when the stop request for
the engine was issued is executed again. And, when it is determined
that the small cam cylinder is included, the switch request for the
drive cam is issued. However, unlike the stop control, the ejection
operations of the pins in all the solenoid actuator is started at
the same timing when the switch request is issued in response to
the start request. After the start of the ejection operations of
the pins, when the retraction operation of the pin in any one of
the solenoid actuators is detected, drive of the fuel injector and
the ignition device in each cylinder is permitted. Hereinafter,
such control during the engine start is also called "start
control".
FIGS. 5 and 6 each are a diagram for describing an example of a
processing routine relevant to the start control executed by the
ECU in the first embodiment of the present disclosure. The routine
shown in FIG. 5 is executed in every time when the start request
for the engine is issued. Note that the presence or absence of the
start request is determine based on, for example, whether or not
the ECU has received the IG signal from the ignition key 46 shown
in FIG. 1. The IG signal is output when a predetermined operation
(for example, the ignition key 46 is turned to a predetermined
position) is executed by a driver of the vehicle.
In the routine shown in FIG. 5, firstly, it is determined whether
or not the drive cam is switched to a starting cam (that is, the
large cam) in all the cylinders (Step S10). The determination in
Step S10 is executed by using the detection result of the return
signal in the stop control executed just before the execution of
this routine. Specifically, when the return signal is detected in
all the solenoid actuators, it is determined that the drive cam has
been switched to the starting cam in all the cylinders. Otherwise,
it is determined that failure of switchover of drive cam in the
stop control has occurred.
When the determination result of Step S10 is positive, it is
estimated that there is no small cam cylinder. Therefore, in this
case, the engine start is permitted (Step S12). Specifically, drive
of the fuel injector and the ignition device in each cylinder is
permitted. On the other hand, when the determination result of Step
S10 is negative, it is estimated that at least one of the cylinder
corresponds to the small cam cylinder. Therefore, in this case, the
switch request for the drive cam is issued (Step S14). Details of a
processing based on the switch request will be described with
reference to FIG. 6.
Following Step S14, it is determined whether the completion of the
retraction operation has been detected (Step S16). The processing
in Step S16 is executed by using the detection result of the return
signal after the processing in Step S14. When the determination
result of Step S16 is positive, it is estimated that the switch
operation of the drive cam has been completed in one of the
cylinders. Therefore, in this case, the ECU proceeds to Step S12.
Unlike the stop control in which the rotation of the cam carrier
may stop during the switch operation of the drive cam, the cam
carrier continues to rotate in the start control. Therefore, in the
start control, the switch operation of the drive cam in each
cylinder is executed one after another according to the ignition
order. Thus, when the determination result of Step S16 is positive,
the engine start is permitted without waiting for the completion of
the switch operation of the drive cam in all cylinders (Step
S12).
The routine shown in FIG. 6 is not only executed when the start
request for the engine is issued, but also is repeatedly executed
at every predetermined control cycle (for example, every 15.degree.
CA).
In the routine shown in FIG. 6, firstly, it is determined whether
or not there is the switch request for the drive cam (Step S18).
When it is determined that there is the switch request for the
drive cam, it is determined whether or not the present processing
is executed during the engine start (Step S20). The processing in
Step S20 is determined based on, for example, an elapsed time from
which the ECU receives the IG signal. When it is determined that
the elapsed time is shorter than the predetermined time (for
example, 1 sec), it is assumed that the present processing is
executed during the engine start. In this case, the ejection
operations of the pins are started simultaneously at all the
solenoid actuators (Step S22).
On the other hand, when it is determined that the elapsed time is
longer than the predetermined time, it is assumed that the present
processing is not executed during the engine start. In this case,
the cylinder discrimination is executed (Step S24). In the cylinder
discrimination processing, it is specified which of the four
strokes the current state of each cylinder is. Subsequently, a
start crank angle of the ejection operation is specified that
allows the pin to be seated on the orthogonal part of the groove
18b (or the groove 18c) in the "pin insertion section" described in
FIG. 3 (Step S26). Then, the ejection operation of the pin is
started when the crank angle has a match to the specified start
crank angle (Step S28).
Following Step S28, it is determined whether or not the completion
of the retraction operations of the pins in all the cylinders is
detected (Step S30). The processing in Step S30 is executed by
using the detection result of the return signal after the
processing in Step S28. When the determination result of Step S30
is negative, the ECU returns to the processing in Step S24. When
the determination result of Step S20 is positive, it is estimated
that the switch operation of the drive cam has been completed in
all the cylinders. Therefore, in this case, the ECU leaves this
routine.
[Example of Switch Operation During Engine Start]
FIG. 7 is a diagram for describing an example of the switch
operation of the drive cam during an engine start according to the
first embodiment of the present disclosure. Like the switch
operation of the drive cam during the normal state of the engine,
the switch operation of the drive cam during the engine start is
executed in response to the switch request. However, during the
engine start, the ejection operations of the pins at all the
solenoid actuators are started at crank angle CA10 at which the
switch request for the drive cam is issued. That is, the ejection
operations of the pins are started without waiting for the
detection of the cam angle signal at crank angle CA11 which is
obtained immediately after the crank angle CA10 due to the chipped
tooth part.
The ejected pin sits on the cam carrier at the crank angle CA12.
The ejected pin does not sit on the cam carrier at the crank angle
CA10 because the starter is started to drive at the crank angle
CA10 and the cam carrier rotates thereafter. At the crank angle
CA12, the pins of the solenoid actuators of #2 cylinder and #4
cylinder are seated on the spiral-shaped groove. At the same crank
angle CA12, the pins of the solenoid actuators of #1 cylinder and
#3 cylinder are seated on an outer periphery of the cam carrier
without sitting on the spiral-shaped groove. Since the pin of the
solenoid actuator of #1 cylinder or #3 cylinder has not been
reached the spiral-shaped groove, the actual timing at which each
of the two pins sit on the spiral-shaped groove is crank angle
slightly after the crank angle CA12. The pin seated on the outer
periphery of the cam carrier moves along the outer periphery in
accordance with the rotation of the cam carrier and then enters
into the spiral-shaped groove from the end portion thereof.
The pin that is seated on the spiral-shaped groove or seated on the
outer periphery of the cam carrier and the entered into the
spiral-shaped groove moves along the groove in accordance with the
rotation of the cam carrier. The earliest finish timing of the
switch operation of the drive cam is at crank angle CA13 (#4
cylinder). When completion of the retraction operation of the pin
is detected at the crank angle CA13, drive of the fuel injector and
the ignition device in each cylinder is permitted. In the example
shown in FIG. 7, therefore, injection from the fuel injector of the
#4 cylinder is executed in crank angle on a retard side relative to
the crank angle CA13, and then the first combustion is occurred in
the same #4 cylinder. Note that the first combustion may be
occurred in #3 cylinder instead of #4 cylinder depending on
injection timing of the fuel injector.
FIG. 8 is a diagram for describing a problem in a case where it is
assumed that the switch operation in the normal state of the engine
described with reference to FIG. 4 is performed during the engine
start. In FIG. 8, the switch request for the drive cam is issued at
crank angle CA10 like the case shown in FIG. 7. Then, based on the
cam angle signal "LO" at crank angle CA11 which is the closest to
the crank angle CA10, the cylinder discrimination is executed.
After the execution of the cylinder discrimination, at crank angle
CA14, the switch operation of the drive cam of #3 cylinder is
started. Also, in accordance with the ignition order of the engine,
the switch operations in the other cylinders are started at crank
angle CA15 (#4 cylinder), crank angle CA16 (#2 cylinder) and crank
angle CA17 (#1 cylinder).
The earliest finish timing of the switch operation of the drive cam
is at crank angle CA18 (#3 cylinder). When completion of the
retraction operation of the pin is detected at the crank angle
CA18, drive of the fuel injector and the ignition device in each
cylinder is permitted. In the example shown in FIG. 8, therefore,
injection from the fuel injector of the #3 cylinder is executed in
crank angle on a retard side relative to the crank angle CA18, and
then the first combustion is occurred in the same #3 cylinder. As
described above, when the switch operation described with reference
to FIG. 4 is executed at the engine start, it takes time until the
first combustion takes place.
In this respect, according to the start control of the first
embodiment, the completion of the retraction operation of the pin
can be detected at the crank angle CA13 described with reference to
FIG. 7. That is, the completion of the retraction operation of the
pin can be detected with crank angle on an advance angle side of
the crank angle CA18 described with reference to FIG. 8. Therefore,
according to the start control of the first embodiment, it is
possible to make the engine to occur the first combustion earlier
(for example, about 400 ms) than a case where the switch operation
of the drive cam is executed likewise the normal state of the
engine.
FIG. 9 is a diagram for describing another example of the switch
operation of the drive cam during the engine start according to the
first embodiment of the present disclosure. In the example shown in
FIG. 9, the switch operations of the drive cams in #2 cylinder and
#4 have been finished at the issue of the switch request is issued
i.e. at the crank angle CA10. This is because the switch operations
in these cylinders was completed in the stop control during the
engine stop just before the current engine start. In this case, the
pins which are ejected at the crank angle CA10 are seated on the
cam carriers at crank angle CA12. At the crank angle CA12, the pin
of the solenoid actuator of #1 cylinder or #3 cylinder does not sit
on the spiral-shaped groove but is seated on the outer periphery of
the cam carrier. The pin seated on the outer periphery of the cam
carrier moves along the outer periphery in accordance with the
rotation of the cam carrier and then enters into the spiral-shaped
groove from the end portion thereof. Up to this point is the same
as the example described with reference to FIG. 7.
In the example shown in FIG. 9, the pin of the solenoid actuator of
#4 cylinder sits on the outer periphery of the cam carrier at the
crank angle CA12. However, unlike the pin of the solenoid actuator
of #1 cylinder or #3 cylinder, the pin of the solenoid actuator of
#4 cylinder moves around the outer periphery in accordance with the
rotation of the cam carrier and then enters into the spiral-shaped
portion from a joint portion thereof. The pin of the solenoid
actuator of #2 cylinder sits on the shallow end portion which
locates on the rear side in the rotational direction than the joint
portion, and then goes back to the solenoid actuator side by the
push from the shallow end portion. Therefore, the earliest finish
timing of the switch operation of the drive cans is at crank angle
CA19 (#2 cylinder). In the example shown in FIG. 9, therefore,
injection from the fuel injector of the #2 cylinder is executed in
crank angle on a retard side relative to the crank angle CA19, and
then the first combustion is occurred in the same #2 cylinder.
The crank angle CA19 is located on an advance side relative to the
crank angle CA18 described in FIG. 8. As described above, according
to the start control described with reference to FIG. 7 or 9, the
completion of the retraction operation of the pin can be detected
at earlier crank angle than the crank angle CA18 described in FIG.
8. Therefore, it is possible to make the engine to occur the first
combustion earlier than a case where the switch operation of the
drive cam is executed likewise the normal state of the engine.
Note that, in the first embodiment described above, the orthogonal
part of the groove 18b or groove 18c described in FIG. 1
corresponds to the "front orthogonal part" of the present
disclosure. The inclined part of the groove 18b or groove 18c
corresponds to the "inclined part" of the present disclosure. The
solenoid actuator 24 corresponds to the "switch mechanism" of the
present disclosure. The ECU corresponds to the "control device" of
the present disclosure. The starter motor corresponds to the
"motor" of the present disclosure.
Second Embodiment
Next, a second embodiment of the present disclosure will be
described with reference to FIG. 10. Note that a configuration
example of a system in the second embodiment is common to the
configuration example shown in FIG. 1. The rotation operation of
the cam carrier and the switch operation of the drive cam are as
described in FIGS. 2 to 4. Therefore, the descriptions about the
system configuration example, the rotation operation of the cam
carrier and the switch operation of the drive cam are omitted.
[Characteristic of Control in Second Embodiment]
In the start control of the above first embodiment, when the switch
request is issued, the ejection operations of the pins at all the
solenoid actuators are simultaneously started. However, such a
switch request is issued after the determination on the small cam
cylinder has executed. The determination on the small cam cylinder
is executed when the start request for the engine is issued. Here,
when the start request for the engine is issued, drive of the
starter is started based on control which is different from the
start control. In the first embodiment, therefore, the ejected pins
are seated on the cam carriers which rotate in accordance with the
drive of the starter.
However, when the ejection operations of the pins are executed
during the rotations of the cam carriers, there is a possibility
that the ejected pin fails to seat on the spiral-shaped groove and
lapses into a semi-engaged state. When the ejected pin lapses into
the semi-engaged state, the pin may be unable to move along the
spiral-shaped groove and the switch operation of the drive cam may
be unexecuted. The switch operation of the drive cam is supposed to
be finished when the pin moves into the spiral-shaped groove while
the cam carrier rotates several times. In the meantime, however,
when the completion of the retraction operation of the pin is
detected in the other cylinder, drive of the fuel injector and the
ignition device in each cylinder is permitted. Therefore, when
there is a pin in the semi-engaged state, there is a possibility
that the same problem occurs as when the switch operation failure
occurs during the stop control.
Therefore, in the start control of the second embodiment, when the
switch request is issued, the eject operation of the pins at all
the solenoid actuators are started while waiting for driving the
starter. Then, when all the ejected pins sit on the cam carriers,
the waiting state of the starter is released. FIG. 10 is a diagram
for describing an example of a processing routine relevant to the
start control executed by the ECU in the second embodiment of the
present disclosure. The routine shown in FIG. 10 is a routine which
is repeatedly executed at predetermined control intervals (for
example, every 15.degree. CA) like the routine shown in FIG. 6.
In the routine shown in FIG. 10, the same processing as the routine
shown in FIG. 6 is basically executed. However, in the routine
shown in FIG. 10, when it is determined in Step S20 that the
present processing is executed during the engine start, drive of
the starter is set to the waiting state (Step S32.) The waiting
state of the starter is realized for example by stopping power
supply from the battery to the starter. Subsequently, the ejection
operations of the pins at all the solenoid actuators are started
simultaneously (Step S34). The processing in Step S34 is the same
as the processing in Step S22 of FIG. 6.
Following Step S34, it is determined whether or not a waiting time
of the starter exceeds a predetermined time (Step S36). The waiting
time is set in advance as a time sufficient for the ejected pin to
sit on the outer periphery of the cam carrier (for example, 100
ms). The processing in Step S36 is repeated until a positive
determination result is obtained. When the positive determination
result is obtained, the waiting state of the starter is canceled
(Step S38).
As described above, according to the routine shown in FIG. 10, it
is possible to rotate the cam carrier by driving the starter after
the pins which are ejected at the start control sit on the cam
carriers. Therefore, the switch operation of the drive cam can be
reliably executed during initial rotations of the cam carriers in
accordance with the drive of the starter.
Third Embodiment
Next, a third embodiment of the present disclosure will be
described with reference to FIGS. 11 to 13. Note that a
configuration example of a system in the third embodiment is common
to the configuration example shown in FIG. 1. The rotation
operation of the cam carrier and the switch operation of the drive
cam are as described in FIGS. 2 to 4. Therefore, the descriptions
about the system configuration example, the rotation operation of
the cam carrier and the switch operation of the drive cam are
omitted.
[Characteristic of Control in Third Embodiment]
In the start control of the above first embodiment, when the switch
request is issued, the ejection operations of the pins at all the
solenoid actuators are simultaneously started. However, since the
energization to the coil is a prerequisite for the ejection
operations of the pins, it is difficult to start the ejection
operation simultaneously at all the solenoid actuators when there
is electrical load restriction.
Therefore, in the start control in the third embodiment, the
ejection operations of the pins are executed for each solenoid
actuator group (for example, a first actuator group and a second
actuator group) in order. FIGS. 11 and 12 each are a diagram for
describing an example of a processing routine relevant to the start
control executed by the ECU in the third embodiment of the present
disclosure. The routine shown in FIG. 11 is a routine which is
executed in every time when the start request for the engine is
issued like the routine shown in FIG. 5. The routine shown in FIG.
12 is a routine which is repeatedly executed at predetermined
control intervals (for example, every 15.degree. CA) like the
routine shown in FIG. 6.
In the routine shown in FIG. 11, the same processing as the routine
shown in FIG. 5 is basically executed. However, in the routine
shown in FIG. 11, it is determined subsequent to Step S14 whether
or not the completion of the retraction operations of the pins of
the second actuator group whose start of the ejection operations of
the pins are executed later (for example, the solenoid actuators on
#1 cylinder and #3 cylinder) is detected (Step S40). The processing
in Step S40 is executed by using the detection result of the return
signal just after the execution of the processing in Step S14. When
the determination result of Step S40 is positive, it is the switch
operation on the drive cam has been completed in one of the
cylinders of the second actuator group. Therefore, in this case,
the ECU goes to Step S12.
In the routine shown in FIG. 12, the same processing as the routine
shown in FIG. 6 is basically executed. However, in the routine
shown in FIG. 12, when it is determined in Step S20 that the
present processing is executed during the engine start, it is
determined whether or not electrical load restriction is exists
(Step S42). The processing in Step S42 is determined based on
whether or not the voltage of the battery feeding the pin of the
solenoid actuator is less than a predetermined value, for example.
When the determination result of Step S42 is negative, the ejection
operations of the pins at all the solenoid actuators are
simultaneously started (Step S44). The processing in Step S44 is
the same as the processing in Step S22 in FIG. 6.
When the determination result of Step S42 is positive, the ejection
operations of the pins of the first actuator group (for example,
the solenoid actuators on #2 cylinder and #4 cylinder) are started
simultaneously (Step S46). The processing in Step S48 is executed
by using the detection result of the return signal after the
processing in Step S46. The processing in Step S48 is repeated
until a positive determination result is obtained. When the
positive determination result is obtained, the ejection operations
of the pins of the second actuator group are started simultaneously
(Step S50).
FIG. 13 is a diagram for describing an example of the switch
operation of the drive cam during the engine start according to the
third embodiment of the present disclosure. In the example shown in
FIG. 13, the switch operations of the first actuator group (that
is, the solenoid actuators of #2 cylinder and #4 cylinder) are
stated simultaneously at the crank angle CA10 at which the switch
request for the drive cam is issued. That is, the ejection
operations of the pins which correspond to the first actuator group
are started without waiting for the detection of the cam angle
signal at crank angle CA11 which is obtained immediately after the
crank angle CA10 due to the chipped tooth part.
The pins which are ejected at crank angle CA12 sit on the
spiral-shaped grooves at the crank angle CA12. The ejected pins
which sit on the spiral-shaped grooves move along the grooves in
accordance with the rotations of the cam carriers. The switch
operations of the drive cam of the first actuator group are
completed at the crank angle CA13 (#4 cylinder) and the crank angle
CA20 (#2 cylinder). The ejection operations of the second actuator
group are started simultaneously at crank angle CA21 on a retard
side relative to the crank angle CA20. In the example shown in FIG.
13, the pins which are ejected at the crank angle CA21 sit on the
spiral-shaped grooves at crank angle CA22. Then the switch
operations of the drive cams of the second actuator group are
executed.
Drive of the fuel injector and the ignition device in each cylinder
is permitted at crank angle on a retard side relative to crank
angle CA23. In the example shown in FIG. 13, the injection from the
fuel injection device of #1 cylinder is executed at crank angle on
a retard side relative to the crank angle CA23, and then the first
combustion is occurred in the same #1 cylinder. As described above,
according to the start control of the third embodiment, it is
possible to make the engine to occur the first combustion earlier
than a case where the switch operation of the drive cam is executed
likewise the normal state of the engine even when there is the
electrical load restriction.
Other Embodiments
In the above described first embodiment, FIG. 1 describes an
example in which four cam carriers 12 are arranged on the cam shaft
10 of the straight four-cylinder type engine. That is, an example
is described in which the cam carriers 12 are arranged per
cylinder. However, the cam carrier 12 may be arranged across two or
more cylinders. That is, the cam carrier 12 may be arranged per
cylinder group. Such an arrangement example is disclosed in JP
2009-228543 A.
In the above described first embodiment, the example is described
in which the cam carrier 12 shown in FIG. 1 has two types of intake
cams 14 and 16 and the drive cam is switched by the two pins 20 and
22. However, the cam carrier may have three or more intake cams. In
this case, it is necessary to arrange the position of the starting
cam and the number of the pins held by the solenoid actuators
appropriately. For example, it is assumed that three types of
intake cams are distinguished into the large cam, the small cam,
and a middle cam based on the working angle and the lift amount.
Then, the starting cam (for example, the large cam) needs to be
provided between the other two cams. In addition, it is necessary
to set the number of the pins of the solenoid actuators to
three.
FIG. 14 is a diagram for describing a cam carrier including three
types of intake cams and a configuration of a solenoid actuator to
be combined with the cam carrier. The cam carrier 50 shown in FIG.
14 has a small cam 52, a large cam 54 and a middle cam 56 in an
adjacent state. On the surface of the cam carrier 50, the
spiral-shaped groove 18 is formed. The configuration of the groove
18 is as described in FIG. 1. The solenoid actuator 58 combined
with the cam carrier 50 has three pins 60, 62, 64 and a coil (not
shown).
FIG. 15 is a diagram for describing an example of a switch
operation of the drive cam during the engine start on the premise
of the cam carrier shown in FIG. 14. In the example shown in FIG.
15, when the switch request of the drive cam is issued, the
ejection operation of the pin 62 is started. When a cam which was
the drive cam immediately before the start request is issued to the
engine (hereinafter referred to as a "cam prior to the starting
cam") is the small cam 52, the drive cam is switched from the small
cam 52 to the large cam 54 in accordance with the movement of the
pin 62 from the groove 18b to the groove 18a (left example of FIG.
15). When the cam prior to the starting cam is the large cam 54,
the drive cam does no switched because the pin 62 seated on the
outer periphery of the cam carrier enters into the groove 18a from
the joint portion and then moves to the groove 18a (middle example
of FIG. 15). When the cam prior to the starting cam is the middle
cam 56, the drive cam is switched from the middle cam 56 to the
large cam 54 in accordance with the movement of the pin 62 from the
groove 18c to the groove 18a (right example of FIG. 15). As
mentioned above, even three kinds of the intake cams are applied,
the first to the third embodiments of the present disclosure can be
worked through the arrangement of the configuration in the cam
carriers and the solenoid actuators.
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